Consider the program:

#include <stdio.h>

int main(void) {
	
	printf("Hello world\mHow are you?");
	
	return 0;
}

Output

    Hello worldmHow are you?

We wanted to print "Hello world" and "How are you?" in separate lines but there is an invalid escape sequence \m. Thus, the result is "Hello worldmHow are you?".

How to fix "Invalid escape sequence in C" error

To fix this and such errors, you should know about all escape sequences and use them properly.

Read: Escape sequences in C

Correct code

#include <stdio.h>

int main(void) {
	
	printf("Hello world\nHow are you?");
	
	return 0;
}

Output

    Hello world
    How are you?